Always test your surface for color reaction in an inconspicuous area first. Clean individual stains prior to an entire area efflorescence cleaning only. Apply the COBBLE PREP solution starting at the lowest point on the surface. For effloresence cleaning, work on 200 – 250 square foot sections at a time. Make sure the cleaner covers all areas. Rinse each section without letting it dry. After the entire area is cleaned, another complete pressure cleaning is recommended. Repeat operation only if necessary.